Fasting every other day may be as effective as a long-term "starvation diet" in extending lifespan, according to a study by The National Institutes of Health.

It is the latest in a series of reports showing that intermittent fasting appears to keep brain and body younger and healthier. Such research challenges nutritional dogma that skipping breakfast and other meals is unhealthy.

Until recently, severely limiting calories was the only scientifically proven way to slow aging and increase lifespan. Dozens of studies since the 1930s have shown that laboratory animals live up to 40 percent longer when the calories in their meals are cut by up to 30 percent.

Scientists assume that severe calorie restriction would do the same in humans, if people could stick with what many would regard as a starvation diet.

"The bottom line is that the beneficial effects we saw with intermittent fasting were as strong or even stronger as the effects with calorie-restriction," said Dr. Mark P. Mattson, chief of the laboratory of neurosciences at the National Institute on Aging. The institute is part of The National Institutes of Health, the government agency that funds most medical research in the U.S.

Mattson's research group at the institute on aging has been probing the effects of intermittent fasting on laboratory mice and rats -- science's prelude to tests in humans.

Evidence of beneficial effects is so strong now that the institute is scripting a clinical trial in people, Mattson said. Some results could be available within six months after the study begins.

"We don't know what will happen in humans, and right now we don't recommend that people try intermittent fasting," Mattson said. Sticking with regular meals is especially important for people with diabetes and other chronic health problems, he indicated.

Nevertheless, Mattson said, "I would be very confident in saying that healthy adults don't need three full meals a day and would be better off skipping one or two. When you go without food, there are benefits. Your cells become more efficient. I haven't eaten breakfast for 20 years."

That's contrary to traditional advice about good nutrition, which stresses the importance of eating a good breakfast and three balanced meals, Mattson acknowledged. But he said there was little scientific basis for those recommendations.

The latest study, published in the Proceedings of the National Academy of Sciences, showed that intermittent fasting had beneficial effects in lab mice that equaled or surpassed those of severe calorie restriction.

Mice that skipped meals every other day had healthier insulin and blood sugar profiles -- which may protect against diabetes -- than those eating either normal or calorie-restricted diets. Brain cells of the intermittent-fasting mice were more resistant to damage in a region associated with Alzheimer's disease in humans.

One previous Institute of Aging study showed that lab rats that fasted every other day for six months had healthier blood pressure and lower heart rates than animals that ate freely.

Others showed that intermittent fasting protected brain cells of lab rats and mice against damage similar to that in strokes, Parkinson's disease and Huntington's disease (a rare, fatal genetic condition) in humans.